Abstract

We demonstrate a new photonically assisted reconfigurable radio-frequency waveform generator. The setup is based on phase modulating a multi-wavelength pulse source and subsequent compression in a dispersive medium. Under the appropriate conditions, we show that the photodetected electrical signal is broadband and coherent. Specifically, we show that this system allows for the synthesis of a reconfigurable finite-impulse-response filter where the number of filter taps is given by the number of wavelengths available from the multi-wavelength source and the reconfiguration is determined simply by their power and wavelength separation. We also show that this technique allows for time-multiplexing the synthesized waveforms, thus leading to an effective switching speed fixed by the clock rate. In particular, we show transitions between synthesized waveforms with a frequency content > 60 GHz in periods shorter than 100 ps.

Figures (8)

(a) Cartoon of the physical process behind the proposed setup: generation of a multiwavelength pulse train where the power and delay can be controlled in the optical domain. (b) Particular proposal in this work.

Illustration of the AWG technique in the static regime. (a)-(d) screen images of the scope for each of the individual taps. (e)-(h) are the corresponding optical spectra in false color. (i) screen image of the optical spectrum when the four lasers are on. (j) and (l) show the achieved electrical waveform in different scale. (k) shows the superposition of the raw data from (a)-(d) and (j).

Triplet and intensity decreasing burst examples. (a) and (e) show the raw data with the superimposed intensities for each tap. (b) and (f) show the screen images of the optical spectra when all the lasers are on and (c-d) and (g-h) show the screen images of the scope traces in different scales.

Time-multiplexing of two different waveforms at a 12 GHz rate. (a) and (b) are the data and data bar gates measured in the optical domain. (c) and (d) the synthesized compressed waveforms coming from EOM1 and EOM2, respectively. (e) and (f) are a zoomed version of (c) and (d). (g) and (h) show the multiplexing possibilities when all the lasers are on.

Time-multiplexing of two different waveforms at a 12 GHz rate with the switching code 1000. (a) and (b) are the data and data bar gates measured in the optical domain. (c) and (d) the synthesized waveforms from EOM1 and EOM2, respectively. (e) and (f) are a zoomed version of (c) and (d). (g) and (h) show the multiplexing possibilities when all the lasers are on.